1. The Field of the Invention
The present invention relates to data input devices and methods, and more particularly to such devices and methods which may be used with display devices.
2. The Prior Art
Display devices are used in a large variety of equipment, for displaying data, messages, instructions, etc. Some of these devices operate in an interactive mode, in which displayed instructions are designed to help the operator perform a desired sequence of operations. For example, when the apparatus is employed as a part of an automatic teller machine, the instructions visible on the display inform the operator of the correct sequence in which to enter his account number, the type of transaction, the amount of the transaction, etc. In the past, it has been customary to provide a set of keys or pushbutton switches, by which the operator may make data entries into the system, or to select one or another program of operations. While the use of separate switches has been generally satisfactory, in enabling the apparatus to perform the intended function, the necessity of providing a separate set of switches or a keyboard increases the size of the overall apparatus, and also reduces the speed with which it may be operated, since the operator's eyes must be diverted from the display to the keyboard and back to the display at frequent intervals. In addition, separate switches must be labeled, and the labels are not readily changeable.
Because of the large amount of electrical noise inherent in the operation of plasma display, it has been considered to be impractical to employ any type of capacitive sensing involving the juxtaposition of a finger of an operator with the exterior surface of the display panel itself. It has been found, however, that the very presence of the noise itself may be utilized in determining the position of an operator's finger, in relation to the display panel. In addition, the present invention is usable with other types of display devices by providing a source of electrical noise for the input device.